Pivoting device for a horology movement including a synthetic bearing

ABSTRACT

A pivoting device for a wheel-and-pinion used in horology including an elastically deformable, synthetic bearing. A pivot point penetrates into and presses against the bottom of a bed in the bearing to limit the axial clearance of the wheel-and-pinion. The lateral surface of the bed includes two frustrum-of-a-cone surfaces that are coaxial and of different angles and that fit together along a circular edge. The lateral surface of the pivot includes a frustrum-of-a-cone surface that extends on either side of the circular edge so that the free annular space between the lateral surfaces of the pivot and the bed is a minimum width at the top of the edge.

United States Patent 1 Schneider PIVOTING DEVICE FOR A HOROLOGY MOVEMENT INCLUDING A SYNTHETIC BEARING [75] Inventor: Jean-Claude Schneider, La

Chaux-de-Fonds, Switzerland [73] Assignee: Fabrique d'horlogerie. Chs. Tissot et iils S.A., Le Locle (Canton of Neuchatel), Switzerland [22] Filed: Oct. 3, I972 [2]] Appl. No.: 294,510

[30] Foreign Application Priority Dita Oct. 8, 197i Switzerland 14737/71 52 'U.s. c|..... 58/140, 308/159 [51] Int. Cl. G04b 13/02, G04b 31/00 [58] Field of Search 58/140; 308/159 [56] References Cited FOREIGN PATENTS OR APPLICATIONS l,927,358 3/1970 Germany 58/l40 July 24, 1973 Primary Examiner-George H. Miller, Jr.

[57] ABSTRACT A pivoting device for a wheel-and-pinion used in bowlogy including an elastically deformable, synthetic bearing. A pivot point penetrates into and presses against the bottom of a bed in the bearing to limit the axial clearance of the wheel-and-pinion. The lateral surface of the bed includes two frustrum-of-a-cone surfaces that are coaxial and of different angles and that fit together along a circular edge. The lateral surface of the pivot includes a frustrum-of-a-cone surface that extends on either side of the circular edge so that the free annular space between the lateralsurfaces of the pivot and the bed is a minimum width at the top of the edge.

12 Claims, 3 Drawing Figures PIVOTING DEVICE FOR A HOROLOGY MOVEMENT INCLUDING A SYNTHETIC BEARING Certain difficulties are encountered in the manufacture of known pivoting devices comprising a bearing, made of synthetic material, having a cylindrically shaped bed, into which is penetrated a cylindrically shaped pivot, particularly when one wishes to make use of a bearing of a synthetic substance that is fairly soft and that is supposed to dampen impacts, thereby protecting the pivots against the dangers of rupture. Indeed, given the fairly small plays which must remain between the bed diameter and the diameter of the pivot, if these two components are not absolutely coaxial but rather slightly oblique with respect to one another, the pivot will touch the lateral side of the cylindrical bed only at its extreme edge. Therefore, the pressures exerted on the synthetic substance in the contact area do reach very high values and this causes a risk of marring the beds flank. This drawback may only be avoided in known constructions by increasing the hardness of the synthetic material at the expense of the impact absorption capacity.

Thus, pivoting devices are known in which part of the device is made of plastic substances that may elastically deform so as to soften the impacts. In some cases the bearing is provided with a bed of a plastic material and is fastened to that structural component to insure wheel-and-pinion pivoting. Then, the pivot is generally rigidly connected to the cated above. In other known constructions, the bearing is provided with, a bed ,of which the lateral wall is bounded by an inner collar, so that the point of the pivot will enter the bed beyond said collar. However, such constructions make use of metallic parts/One cannotconceive of constructing them in a plastic substance.

Pivoting devices are also known in which a plastic pivot of cylindral-conical shape enters-a bed which is bounded by an inner collar that guides the pivot lateral side. Thepivot is fixed whereas the bearing is fastened to the arbor of the wheel-and-pinion. In this case, however, the axial stop is achieved by shoulders that are provided around the pivot and in the outer lateral side of the wheel-and-pinion arbor.

. Such an arrangement is known for devices used in electrical appliances that operate in a fixed position and, as they are meant for the upper journal of the 'wheel-and-pinion, their application to horology parts is not possible. v

The purpose of the present invention is to achieve a pivoting device for a horology wheel-and-pinion in which-the bearing is made of a synthetic substance which may elastically deform so as to dampen impact and in which the drawback mentioned above is eliminated due to an arrangement that also allows a simplification of the wheel-and-pinion manufacture.

To that end, the purpose of the present invention is the design of a pivoting'device for a wheel-and-pinion used in horology. The pivot comprises a synthetic bearing that will elastically deform and has a bed into which penetrates a pivot with the point of the pivot pressing against the bottom of the bed in order to limit the axial clearance of the wheel-and-pinion. The lateral surface of the bed comprises two frustrum-of-a-cone surfaces that are coaxial and that are of different angles, fitting together along a circular edge. The lateral surface of the pivot comprises a frustrum-of-a-cone surface that extends on either side of said edge, the free annular space between said lateral surfaces being of minimum width at the height of said edge.

In the sense used herein, the expression frustrum-ofa-cone surface also encompasses the particular case where the apex of said surface lies at infinity, that is, for the case of a right cylindrical surface segment.

The attached drawings illustrate two embodiments of the device according to the invention.

FIG. 1 is a section in diagrammatic form showing the essential characteristics of the pivoting device described below.

FIGS. 2 and 3 are axial sections of two horology balances provided with pivoting devices according to two different forms of embodiments of the invention.

In FIG. 1, organ 1 is ametal pivoting capsule made by profile-turning. This part may be a fixed part which is force-fitted into an opening of a structural element of a horology movement or it may be a movable part which is fastened to the arbor of a rotational organ of that movement; Organ 2, which constitutes the bearing, either is a movable piece or a fixed piece. It may be seen that bearing 2,, which may be achieved by synthetic injection, is provided on its side facing pivot 1 with bed 3. The lateral surface of bed 3 which surface is a revolution about its axis, comprises a cylindrical part 4 bounded'by a plane base 5, forming the bottom of the bed, and by a frustrum-of-a-cone part 6 that forms its entry stretches to a frontal surface of the hearing. The two coaxial frustrum-of-a-cone surfaces fit together along a circular edge 7.

Capsule 1 comprises a pivot 8 the shape of which is slightly of a frustrum-of-a-cone and the height of which is larger than that of cylindrical surface 4 which makes up the bottom of bed 3. Beyond pivot 8, there is a reinforcing zone 9 which is also in the shape of a frustrumof-a-cone but of a larger opening. Reinforcing zone 9 stretches to the collar 10 which is of circular form and through capsule 1 fastens to its supporting organ.

The bottom 5 of bed 3 extends to within a very small distance (a few hundredths of a mm) of side 11 of the bearing, so that these two surfaces bound a thin veil 12 that makes up the bottom substance of bed 3. When the pivoting device is being assembled, a metallic part 13 with a plane side will be placed against surface 11 and thus any plastic deformation of veil 12 will be suppressed when the point of pivot 8 does press against this latter part of bearing 2.

In general, the device as described and specified provides the following advantage. The annular space between pivot 8 and the inner surfaces of bed 3 is of minimum width at the height of edge 7, so that even if perfect coaxial alignment between pivot l and bearing 2 is not realized, that is, even if one of those axes should be oblique with respect to the other, the part of pivot 8 whichwill touch the flank of bed 3 will be an areaof the lateral surface of pivot 8 that is located at the height of edge 7, and this area will come intocontact with edge 7. In this manner one avoids the pivot edge, having a hard substance, from touching and marring the lateral surface of bed 3.

Another advantage of the described device is that in case of radial impact, the support of pivot 8 with respect to edge 7 causes a slight deformation of the synthetic substance of the bearing in the vicinity of that edge. The contact surface increases as a function of the deformation, and consequently, as a function of the magnitude of the impact, the loads in the pivot substance are distributed and this decreases the danger of rupture. Furthermore, the presence of the reinforcing zone 9, of which the lateral side is a frustrum-of-a-cone surface of the same opening as entry 6, will insure complete protection of the pivot when there is an appreciable radial impact. This is because the deformation of edge 7 in such a case will be such that the reinforcing zone 9 touches, along its entire height, the entry 6 of the bed. Therefore, the zone under load near the base of the pivot and the contact surface will momentarily reach a much larger magnitude than under normal conditions.

Achieving the advantages described above does not require the pivot point to be slightly in the shape of a frustrum-of-a-cone or the bottom of the bed to be cylindrical. Other arrangements may also apply. The pivot point, for instance, may be cylindrical if that part forming the bottom of the bed is in the shape of a frustrum-of-a-cone with an opening directed inversely to the direction of entry 6. However, it is particularly advantageous that a bed be manufactured having a bot- .tom which is cylindrical and which is emplaced in a bearing obtained by injection.

FIGS. 2 and 3 show two embodiments of horology balances which are provided with pivoting devices according to the principle shown in FIG. l.'ln those two forms of embodiments, the pivoting capsules 1 are fixed and attached to components of the structure 14 and 15 which constitute the bottom plate and a horology movement bridge. In the embodiment shown in FIG. 2, one of thebearings 2 is molded in one piece with a central part 16 and with the arms of the balance. The central part 16 is provided on its side opposite to bearing 2 with a cylindrical bed 17 into which penetrates an end from a cylindrical arbor component 18. The extreme side of arbor 18 makes up the metallic surface 13 that extends slightly from the bottom of bed 3 of the bearing.

At its other end, arbor l8 penetrates in the same manner into a bed 17 which is fashioned in a part of synthetic substance 20 in the shape of a cap or chape. Synthetic substance 20 comprises the balance roller having a projection 21 constituting the roller pin and an end cylindrical part in which has been fashioned an entry hollow of the guard pin and a bed 3 which is identical with the one in the central bulge of part 16. Between parts 20 and 16, there is a collet 22 which accepts the inner end of the balancespring. It may be noted that the arbor component 18 is provided with a semi-flat part 19 in order to allow evacuation of the air from the beds 17 when the balance is being assembled.

In this fashion, one achieves an extremely simplified assembly, since it is enough to force-fit capsules 1 into the openings provided in the structural components 14 and I5 and since it suffices to assemble the two parts 16 and 20 upon arbor 18 after having put collet 22 at the center of that arbor. The balance rim is fastened to the radial arms of the central part 16 by means which are not shown. The balance, therefore, is supported in the axial direction between the ends of pivots 8 that may press against the bottom of bed 3 and is supported in the radial direction by the flanks of pivots 8 which touch the edges 7 of bed 3 by their lateral surface, thereby eliminating marring of the synthetic matter and allowing for softening of radial impacts.

In the embodiment shown in FIG. 3, the two bearings 23 are provided with bed 3 identical to that used in the bearings 2. They are fastened to both ends of a cylindrical arbor component 24 by means of a central part 26 of a balance and by means of roller 27. These two parts are metallic and have been provided with axial reaming which was fitted to the bearings 23 and to arbor 24. They are partly force-fitted to arbor 24 and to the central part of bearings 23 after engaging collet 25 on the central part of arbor 24. 7

Despite the simplicity, the construction modes shown in FIGS. 2 and 3 insure good concentricity for the rim and for the roller pin with respect to the axis of the de vice. For instance, in the case of FIG. 2, it is enough that the beds 3 and 17 of parts 16 and 20 be coaxial for all the components of the balance, once they have been assembled, to be perfectly concentric. Similarly in the case of FIG. 3, it is enough to insure coaxial arrangement of beds 3 with the outer lateral sides of bearings 23. Furthermore, arbors 18 and 24 do not require any other manufacturing operation than cutting to the desired length from a bar ofsuitable diameter. The balance of FIG. 2 requires only grinding of the semi-flat part 19.

Whereas the two embodiments described above comprise pivoting capsules which are fixed and bearings which are fastened to the movable part, the inverse arrangement may also be achieved. In such a case, the reinforcing zone 9 and point 8 of the capsule 1 may be directly fashioned at the ends of the arbor, with. the bearings which are similar to the bearing 23 beingfixed in beds fashioned in the structural components in such a case. Preferably, the beds for accepting the hearings will be blind so that the thin film of substance remaining below the bottom of beds 3 will be supported by the metal or by the rigid substance of the component.

What is claimed is: A

l. A pivoting device for a horology wheel-and-pinion comprising a bearing having a bed, of a synthetic, elastically deformable material; and a pivot which penetrates into the bed, the point of which presses against the bottom of the bed in order to limit the axial clearance of the wheel-and-pinion; said bed comprising a first lateral surface having two surfaces, one of which is a frustrum-of-a-cone, the other being a cylinder, both surfaces being coaxial with one another and joined together along a circular edge; said pivot comprising a second lateral surface having a frustrum-of-a-cone surface that extends on either side of said edge, the free of different angles and join together along a circular edge; said pivot comprising a second lateral surface having a frustrum-of-a-cone surface that extends on either side of said edge, the free annular space between said first and second lateral surfaces being of minimum width at the height of said edge.

3. A device according to claim 1 wherein the bearing bed comprises an entry bounded by a frustrum-of-acone surface and by a bottom laterally limited by a cylindrical surface.

4. A device according to claim 1 wherein the bearing is fastened to the arbor of the horology wheel-andpinion, the latter comprising the balance of a watch movement, and wherein the pivot is made of one piece with a collar and is fastened to a structural component of said movement.

5; A device according to claim 1 wherein the pivot comprises a collar, a reinforcing zone in the shape of i a frustrum-of-a-cone and a point limited by said frustrum-of-a-cone surface of the pivot, the angles sub-' projects from a collar which is made of one single piece with the pivot, said collar being cylindrical in shape and being of a diameter larger than that of the pivot base so that it may be force-fitted into an opening of said structural element.

9. A device according to claim 1 wherein the bottom of the bed of the bearing is axially supported by a metallic part which has a planesurface touching the side of the bearing that is opposite to the bed so as to allow only a veil of synthetic substance between the bottom of the bed and that plane side.

10. A device according to claim 9 wherein the bearing is molded in one piece with another part of the wheel-and-pinion.

11. A device according to claim 10 wherein said metallic part comprises a component of an arbor mounted in a cylindrical bed which is fashioned in another part of the wheel-and-pinion.

12. A watch movement balance comprising a metallic arbor; bearings of an elastically deformable synthetic substance, fastened to the two ends of said arbor, each said bearing being provided with a bed of cylindrical-conical shape, said bearings being pivoted between two structural components each provided with a pivoting capsule, each capsule being provided with a pivot penetrating into one of said beds, said pivot being provided with a frustrum-of-a-cone lateral side at its end which extends on either side of the edge which bounds the cylindrical part of the frustrum-of-a-cone part of the bed. 

1. A pivoting device for a horology wheel-and-pinion comprising a bearing having a bed, of a synthetic, elastically deformable material; and a pivot which penetrates into the bed, the point of which presses against the bottom of the bed in order to limit the axial clearance of the wheel-and-pinion; said bed comprising a first lateral surface having two surfaces, one of which is a frustrum-of-a-cone, the other being a cylinder, both surfaces being coaxial with one another and joined together along a circular edge; said pivot comprising a second lateral surface having a frustrum-of-a-cone surface that extends on either side of said edge, the free annular space between said first and second lateral surfaces being of minimum width at the height of said edge.
 2. A pivoting device for a horology wheel-and-pinion comprising a bearing having a bed, of a synthetic, elastically deformable material; and a pivot which penetrates into the bed, the point of which presses against the bottom of the bed in order to limit the axial clearance of the wheel-and-pinion; said bed comprising a first lateral surface having two frustrum-of-a-cone surfaces which are coaxial with one another and which are of different angles and join together along a circular edge; said pivot comprising a second lateral surface having a frustrum-of-a-cone surface that extends on either side of said edge, the free annular space between said first and second lateral surfaces being of minimum width at the height of said edge.
 3. A device according to claim 1 wherein the bearing bed comprises an entry bounded by a frustrum-of-a-cone surface and by a bottom laterally limited by a cylindrical surface.
 4. A device according to claim 1 wherein the bearing is fastened to the arbor of the horology wheel-and-pinion, the latter comprising the balance of a watch movement, and wherein the pivot is made of one piece with a collar and is fastened to a structural component of said movement.
 5. A device according to claim 1 wherein the pivot comprises a collar, a reinforcing zone in the shape of a frustrum-of-a-cone and a point limited by said frustrum-of-a-cone surface of the pivot, the angles subtended by the point being smaller than that of the reinforcing zone.
 6. A device according to cLaim 5 wherein the frustrum-of-a-cone surfaces of the pivot reinforcing zone and of the bed entry subtend the same angle.
 7. A device according to claim 1 wherein the pivot is fastened to a structural component of a horology movement and the bed is fashioned in a part of the wheel-and-pinion.
 8. A device according to claim 7 wherein the pivot projects from a collar which is made of one single piece with the pivot, said collar being cylindrical in shape and being of a diameter larger than that of the pivot base so that it may be force-fitted into an opening of said structural element.
 9. A device according to claim 1 wherein the bottom of the bed of the bearing is axially supported by a metallic part which has a plane surface touching the side of the bearing that is opposite to the bed so as to allow only a veil of synthetic substance between the bottom of the bed and that plane side.
 10. A device according to claim 9 wherein the bearing is molded in one piece with another part of the wheel-and-pinion.
 11. A device according to claim 10 wherein said metallic part comprises a component of an arbor mounted in a cylindrical bed which is fashioned in another part of the wheel-and-pinion.
 12. A watch movement balance comprising a metallic arbor; bearings of an elastically deformable synthetic substance, fastened to the two ends of said arbor, each said bearing being provided with a bed of cylindrical-conical shape, said bearings being pivoted between two structural components each provided with a pivoting capsule, each capsule being provided with a pivot penetrating into one of said beds, said pivot being provided with a frustrum-of-a-cone lateral side at its end which extends on either side of the edge which bounds the cylindrical part of the frustrum-of-a-cone part of the bed. 